Water-based solar module cleaning tech for rooftop PV


A group of researchers from the National University of Sciences & Technology (NUST) in Pakistan has designed a novel solar module cleaning technology that also has a cooling effect on the PV modules.

“The proposed solar panel cleaning system can be effortlessly integrated into both residential and commercial solar PV installations,” the research's lead author, Adeel Waqas, told pv magazine. “Designed to function autonomously, the system uses a microcontroller to manage the cleaning process, eliminating the need for manual intervention.”

The cleaning system consists of a 76.2 cm long bar of steel that is attached to the upper side of the solar module. It has eight flat-fan nozzles that provide a uniform flow of water through the panel's front side via a convex spray pattern. The fan nozzles are placed at a distance of 14 cm from each other and can achieve a water flow of 0.49 L/m. A 36 W DC water pump is used to bring water into the bar.

“After cleaning, the used water is collected and filtered using a Whatman filter,” Waqas explained. “This process allows for a water recovery efficiency of 85%, with the filtered water being recycled back into the system's tank. The water recovery feature makes this system especially beneficial for regions facing water scarcity.”

The scientists tested their new technique at an experimental setup at the NUST in Islamabad, Pakistan, during the months of January and February for three PV system tilt angles of 23, 33, and 43 degrees, respectively. “The electrical and temperature parameters were constantly monitored over 24 h, with 1 min intervals between each set of values,” they specified, noting that the performance of the system was compared to that of a reference setup without the cleaning tech.

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Through their analysis, the academics found that the cleaned PV panel achieved up to 13.74% higher current at the set tilt angles compared to the reference panel. They also found that the water flowing onto the module was able to reduce its operating temperature by up to 0.8 C compared to the benchmark setup. “The automated cleaning system, operating for 5 min daily with pressured water through flat fan nozzles, recovers power loss due to soiling up to 80%,” they added.

According to Waqas, the cost of the Solar PV module with the cleaning system is $65.48, while that of the module without the system is around $35. “After performing the economic analysis, the cost recovered from additional power after cleaning is $0.0332 per day, resulting in a payback period of 2.51 years in Islamabad for additional cleaning system costs,” he further explained. “The operating cost of the system is negligible since it is automatically operated using an Arduino board; also, the economic feasibility of the proposed system is relatively viable since the cost of the system is recovered in a short time.”

The new technique was presented in the study “A building integrated solar PV surface-cleaning setup to optimize the electricity output of PV modules in a polluted atmosphere,” which was recently published in Renewable Energy.

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